Process for drying polyamide fibers catonic dyes and zinc thiocyanate

ABSTRACT

Process for dyeing polyamide fibers with a cationic dye comprising treating said fibers with an aqueous bath containing a cationic dye and zinc thiocyanate at a temperature of at least 90* C.

United States Patent Leung PROCESS FOR DRYING POLYAMIDE FIBERS CATONIC DYES AND ZINC THIOCYANATE [72] Inventor: Peter S. K. Leung, Wilmington, Del. [73] Assignee: E. I. du Pont de Nemours and Company,

Wilmington, Del.

[22] Filed: Aug. 28, 1969 [2]] Appl. No.: 853,924

[52] US. Cl ..8/30, 8/178 51 1m.'c1. ....D06p 3/24 [58] Field of Search ..8/l78 R, 175,172, 166,177 AB,

[56] References Cited UNITED STATES PATENTS Biederman Hill et al.....

Kwolek et a]. "2611/78,

[ 51 Mar. 28, 1972 R. W. SchumrnLet al.,- iA publication by AATCC), Aug. 27, 19 9, v61. 1,615. 1 s; pages 27- 30 Primary ExaminerDonaId Levy Assistant Examiner-T. J. Herbert, Jr.

; Attorney.lohn E. Dull 57] ABSTRACT Process for dyeing polyamide fibers with a cationic dye comprising treating said fibers with an aqueous bath containing a Q cationic dye and zinc thiocyanate at a temperature of at least 5 Claims, No Drawings PROCESS FOR DRYING POLYAMIDE FIBERS CATONIC DYES AND ZINC THIOCYANATE BACKGROUND OF THE INVENTION This invention concerns a process for dyeing polyamide fibers with cationic dyes. These dyes are of particular interest for use in polyamides because of their bright shades, particularly in the red and pink colors and because of the fluorescence which some of the cationic dyes display.

Polyamide fibers have been the subject of much research in the field of dyeing, and numerous dyes are available, particularly in the disperse dye and acid dye categories. However, the cationic dyes have been characterized by poor affinity and poor wash fasteners when applied to polyamide fibers. Fibers of polyamides containing aromatic or cyclohexane constituents are especially resistant to cationic dyes.

SUMMARY OF THE INVENTION The present invention provides a process for dyeing polyamide fibers with a cationic dye comprising contacting said fibers with an aqueous bath containing a cationic dye and zinc thiocyanate at a temperature of at least 90 C., the amount of zinc thiocyanate in the bath being from 1 to 60 percent based on the weight of said fibers and less than 1.5 percent based on the weight of water in the bath. This invention provides a process whereby cationic dyes can be applied to polyamide fibers in much the same manner as disperse dyes, i.e. by dissolving in the fiber and diffusing through it. The process is particularly useful for the polyamides containing aromatic constituents or cyclohexane constituents.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The polyamide fibers which may be dyed by the process of this invention include all of the commonly known polyamides such as poly(hexamethylene adipamide), the polymers obtained from f-caprolactam, and copolymers of these. The process is particularly useful for application of cationic dyes to fibers of polyamides containing aromatic constituents, such as disclosed in US Pat. No. 3,063,966, and polyamides containing cyclohexane constituents, such as disclosed in US. Pat. No. 3,393,210. The preferred polyamides are poly(metaphenylene isophthalamide) and the polymer derived from bis(4-aminocyclohexyl)-methane and dodecanedoic acid, i.e., poly(methylene-di-l ,4-cyclohexylene dodecane diamide).

The cationic dyes (sometimes known as basic dyes), in general, are chemical mixtures containing compounds with one or more onium groups such as the quaternary ammonium group. The onium groups carry a positive charge; hence the name cationic." The principal constituent may also contain some anionic water-solubilizing groups such as sulfonic or carboxylic acid groups provided that there are more equivalents of the cationic groups then of the anionic groups. A large number of suitable cationic dyes is disclosed in Canadian Pat. No. 794,953. Other useful cationic dyes are disclosed in US. Pat. No. 3,338,660.

The aqueous dye bath used in this invention must contain zinc thiocyanate which promotes high color yield and high wash fastness without affecting appreciably the physical properties of the fiber. The color yield for cationic dyes applied to polyamide fibers in the presence of zinc thiocyanate is usually at least 2.5 times as great as the color yield without zinc thiocyanate. The color yield of the dyed fibrous polyamides is measured by the K/S value (Kubelka-Munk absorption-scattering factor) which is calculated from the expression K/S i lR) /2R where R is the fraction of light reflected at maximum absorption wavelength from the dyed yarn or fabric. To obtain a relative color yield the K/S value for dyeing in the presence of the anionic agent is divided by the K/S value obtained in the absence of the anionic agent and multiplied by 100. In the process of the invention, the dye bath may contain zinc thiocyanate or its equivalent ionic components. It should be understood that the zinc cations, thiocyanate anions, or thiocyanate complex ions may be supplied from separate chemicals. It is only essential that the zinc cation and thiocyanate anion be available in sufficient quantity to give 1 to 60 percent of the equivalent zinc thiocyanate based on the weight of the fibers and less than 1.5 percent by weight based on weight of water in the bath.

Analysis of polyamide yarns after dyeing indicates that zinc and sulfur atoms are present in a 1:4 ratio. This ratio seems to indicate that a complex is formed between the zinc thiocyanate and the dye molecule, the composition being perhaps, [Dye*];. [Zn(SCN)4]. Therefore, the zinc ion and the thiocyanate ion are no longer present in the 1:2 ratio of Zn(SCN) The 1:4 ratio is maintained regardless of dye concentration. The dye complex may possibly act through a disperse dyeing mechanism. The ratio by weight of zinc thiocyanate to the dye weight is not critical, and in fact the optimum thiocyanate concentration in the bath may be considerably more than would be required to provide one equivalent of zinc for one equivalent of dye. It is believed that the additional zinc thiocyanate acts as a swelling agent for the fiber and for the dye complex thereby promoting diffusion.

It is surprising to note that other thiocyanates are relatively inferior in promoting the dyeing of polyamides with cationic dyes. The superiority of zinc thiocyanate is not completely understood, but it is definitely superior to other thiocyanates.

While the aqueous dye bath need not contain any additional dye carriers, it is often desirable to use such dye carriers when difficultly dyeable polyamide fibers are being processed. In particular, dye carriers are useful in dyeing poly(meta-phenylene isophthalamide) fibers and poly-(methylene-di-l ,4- cyclohexylene dodecane diamide) fibers. Suitable dye carriers for these two types of fibers include butyl benzoate, pelargonic acid, mixtures of benzanilide and dirnethyl terephthalate, o-phenyl phenol, chlorinated benzene, biphenyl, and methyl salicylate.

In the practice of this invention, the temperature of the aqueous dye bath is at least 194F. (C.), but usually less than about 270F. (132C). Obviously, adequate pressure equipment must be provided for dyeing in aqueous baths at temperatures above 212F. (C).

In this invention, the aqueous dye bath preferably is acidic. Conventional dye bath additives also may be used, if desired, such as surface active agents and leveling agents. Citric acid is a particularly desirable leveling agent.

The following examples further illustrate preferred embodiments of this invention. In these examples, poly(metaphenylene isophthalamide) is abbreviated MPD-I and poly- (methylene-di-l,4-cyclohexylene dodecane diamide) is abbreviated PACM-l2. In these examples, all percentages are on a weight basis.

EXAMPLE I EFFECT OF ZINC TI-IIOCYANATE CONCENTRATION ON COLOR VALUE FOR MPD-I SAMPLES Ten swatches of fabric woven from MPD-l fibers weighing 10 g. each are introduced into 10 separate aqueous baths at 100F. (38C.). Each bath contains 0.1 G. Merpol HCS (a nonionic surfactant), 1.5 gm. Latyl Carrier A (a mixture of benzanilide and dimethyl terephthalate), 4 g. glacial acetic acid, 0.3 g. Calcozine Acrylic Blue H? (a cationic dye, Color Index Basic Blue 54). Each bath contains a different amount of zinc thiocyanate as indicated in Table l. The baths containing the fabric samples are heated to 250F. (121C.) and kept at this temperature for 2 hours. After this the samples are removed from the baths and rinsed. Then the dyed samples are scoured for 30 minutes in 400 ml. of aqueous bath containing 0.1 g. Merpol HCS (nonionic surfactant) and 0.1 g. tetrasodium pyrophosphate at a temperature of 200F. (93C.). The dyed and scoured material is then rinsed and dried. A series of blue dyed fabric samples are obtained which have good wash fastness. The color yield for each of the dyeings is indicated in Table'l.

. of various dye carriers on color yield measured by the K/S TABLE 1 6 71m: Thiocyanare Based on Based on K/S Relative Bath Water Fiber Value Color Yield 1 o o oss 100 2 0.125 5 2.2.4 254 3 0.250 10 2.45 279 4 0.515 2.20 250 5 0.500 to 2.20 250 a 0.625 1.22 1311 1 0.150 50 1.11 195 a 0.515 :15 1.55 116 1 5 9 1.000 40 1.67 1119 10 1.25 45 1.59 181 EXAMPLE 11 EFFECT OF ZINC THIOCYANATE CONCENTRATION ON CATIONIC DYEING OF PACM-l2 Twenty-one swatches of fabric woven from PACM-12v 25 fibers, each weighing 5 g., are introduced into'21 separate 200 ml. warm baths (38C.). Seven of the baths contain 0.1 g."Astrazon Yellow 7GLL (a cationic dye, Color Index Basic Yellow 21 Seven others contain 0.1 g. Sevron" Brilliant Red D (a cationic dye, Colorindex Basic Red 19). Another seven contain 0.1 g. Sevron Blue EG (a cationic dye, Color Index Basic Blue). Each of the baths also contains 4 g. citric acid, 0.05 g. Merpol" I-ICS, 0.75 g. Cindye DAC 888 (butyl .benzoate) and zinc thiocyanate as indicated in Table 2. The baths are heated to 212F. (100C.) and kept at this temperature for 90 minutes. The dyed swatches are then removed from the dye bath and rinsed. Then they are scoured for 30 minutes at 180F. (82C.) in 200 ml. aqueous baths containing 0.05 g. Merpol HCS and 0.05 g. tetrasodium pyrophosphate. The swatches are then rinsed and dried. A se- 40 ries of yellow, red, and blue dyeings are obtained which have good wash fastness.

The efiect of zinc thiocyanate concentration on color yield as measured by the K/S valueis indicated in Table 2.

TABLE 2 I: Zine Thiocyanare EFFECT OF VARIOUS DYE CARRIERS ON CATIONIC DYEING MPD-I Ten swatches (10 g.) of MPD-I woven fabric are introduced into 10 separate aqueous baths at 100F. (38C.) each containing 0.1 g. Merpol" I-ICS, 4 g. glacial acetic acid, 4.0 g. zinc thiocyanate (1 percent based on,wa ter, 25 percent based on fiber), 0.3 g. Calcozine" Acrylic Blue HP (Color Index Basic Blue 54) and 1.5 g. of a dye carrier. Several separate dyeings were run, each with a different dye carrier.- The effects 4 value are listed in Table 3. The carriers were added in sufficient quantity to give 15 percent by weight, based on fiber. The 10 baths each containing a different carrier or no carrier were heated to 250F. 121C.) and kept at this temperature for 2 hours. The dyed materials were then removed from each of the dye baths and rinsed. Then the dyed materials were scoured for 30 minutes in 400 ml. of another aqueous bath containing 0.1 g. Merpol l-lCS and 0.1 g. tetrasodium pyrophosphate at a temperature of 200"F. (93C.). The dyed and scoured materials were then rinsed and dried. A series of blue dyeings is obtained which have good wash fastness.

TABLE 3 Dye Carrier Color Yield KIS None 1.154

Phenetor D 1.600

Mixture of emulsified organic solvents Cindye" DAG-888 1.713

Butyl benznate Pelargonic Acid 1.542

Latyl" Carrier A 1.883

Mixture of benzsnilide and dimethyl terephthalate Carolid" 50 2.010

o-Phenylphenol "Chemo Carrier KDSW 1.179

Dimethyl phthalate v "Tanavol" 1.646

Chlorinated benzene "Charlab" M-1 1.613

Biphcnyl Methyl salicylate 1.624

EXAMPLE IV Swatches (5 g.) of PACM-IZ wovenfabric are introduced into 51 separate aqueous baths at F. (38C.). Each of the baths contains 200 ml. of water, 4 g. citric acid, 0.05 g. Merpol I-ICS, 2 g. zinc thiocyanate (1 percent based on water, 40 percent based on fiber), and 0.75 g. of one of the dye carriers shown in Table 4. In addition, one of the three dyes shown in Table 4 is added. In each case the amount of dye is 0.1 g. The bath is then heated to 212F. (100C.) and kept at this temperature for 90 minutes. The dyed fabric samples are then removed from the dye baths and rinsed. Then, the dyed samples are scoured for 30 minutes at 180F. (82C.) in 200 ml. of another aqueous bath containing 0.05 g. Merpo1" HCS and 0.05 g. tetrasodium pyrophosphate. The dyed and scoured materials are then rinsed and dried. A series of orange, red and blue dyeings are obtained which have good wash fastness.

The efi'ect of various dye carriers on color yield is determined by measurement of K/S values for the dyed fabrics. Fabrics which were dyed in the same way but without carrier were also measured. The resulting data are given in Table 4. It is obvious that a wide variety of carriers may be used. The preference for any one of these is dependent upon other properties besides color value, e.g. wash fastness, physical properties of fiber, heat stability, and light fastness.

TABLE 4 Cationic Dyer "Maxilon" Brillisnt "Sevron" Orange Brilliant "Sevron RA Red D Blue 50 (Color (Color (Color index Index Index Basic Basic Basic Dye Carrier Orange) Red 19) Blue 4) None 0.0819 0.536 0.385

Cindye" DAG-888 1.497 5.425 5.836

Butyl benzoate Latyl Carrier A 1.423 4.939 6.323

Mixture of benzanilide and dimethyl terephthalate "Carolid" 1.530 6.845 7.070

o-Phenylphenol Tanavol" 1.576 5.433 6.869

Chlorinated benzene "Phenetol" D 1.700 5.704 5.794

Mixture of emulsified mgsnlc mlvenul mmclhyl phtlmlll:

"1 nnnlld" 004 0.607 25.0 2.970

p-Phenylphcnol "Charlab M-S 1.187 3.810 4.837

methyl nlicyllte Pelsrgonlc Acid 1.838 4.830 6.931

Octyl Alcohol 0.641 6.690 3.170

Benzyl Alcohol 0.207 1.674 8.532

Dimethyl Sulfone 0.361 2.500 2.450

Benzoic Acid 0.410 3.090 2.620

Dimethyl phthalste 1.519 1.325 1.486

Hexanol 1.019 2.830 7.447

Methyl Salicylate 1.046 5.704 5.812

EXAMPLE V EFFECT OF TEMPERATURE ON DYEING OF MPD-l Swatches of MPD-l woven fabric, each weighing 10 g. are introduced into twelve 400 ml. aqueous baths each containing 0.3 g. of one of the dyes indicated in Table 5. Each of the baths also contains 0.1 g. Merpol HCS, 1.0 g. zinc thiocyanate (0.25 percent based on weight of water, 10 percent based on weight of fiber), 3.5 g. of Latyl" Carrier A and 4.0 g. glacial acetic acid. The dye baths are heated to the temperatures indicated in Table and maintained at this temperature for 2 hours. Identical dyeings are performed at 212F., 230F., 250F., and 270F. (100C, 110C.', 121C., and 132C, respectively). The dyed material is then removed from the baths and rinsed. Then the dyed material is scoured for 30 minutes at 200F. (93C.) in 400 ml. of another aqueous bath containing 0.1 g. Merpol l-lCS and 0.1 g. tetrasodium pyrophosphate. The dyed and scoured materials are then rinsed and dried. A series of yellow, red, and blue dyed fabrics is obtained, each having good wet fastness.

The effect of temperature on relative color yield measured by the K/S value is exhibited in the following Table 5.

Samples dyed at 250 F. (121 C.) were arbitrarily assigned as 100.

EXAMPLE VI DYEING OF MIXED FILAMENT YARN A mixed filament yam of 60 denier containing 18 filaments of PACM-12 and 18 filaments of a copolymer derived from bis(4-aminocyclohexyl)methane and a mixture of diacids composed of 90 mole percent dodecanedioic acid and mole percent isophthalic acid is prepared for dyeing in a package dyer. Twenty-four ia-lb. packages are prepared using yarns having 5 turns/inch (2 tums/cm.) Z twist. The yarns are first packaged on collapsible mufis and are then preshrunk by treatment in a steam autoclave at 127C. for 30 min. The yarn from the muff is then rewound onto 24 perforated steel cylinders. The cylinders are then loaded into a 48 gallon kier with a 5 gallon expansion tank. All subsequent steps, e.g. scouring, dyeing, etc., are conducted at maximum capacity of the kier. The bath:fiber weight ratio if 35:1 for a 12 1b. yarn load. Direction of liquor flow in the kier is changed every three minutes.

The preshrunk yarn is scoured with 54.5 g. each of Merpol HCS and tetrasodiurn pyrophosphate for 20 minutes at 1 F. (82C.) to remove finishes or oils applied during earlier processing. A fresh bath containing 54.5 g. Merpol RC8 (l), (2) and (3), respectively, whose formulae are given below:

After ten minutes, 2,180 g. of a 50 percent aqueous solution of zinc thiocyanate is added [0.5 percent Zn(SCN), based on water, 20 percent based on fiber, 1,760 percent based on dye]. After 10 minutes, the bath is raised to 240F. (1 16C.) at a rate of 3F./min. l.67C./min.). At F., 1,635 g. of butyl benzoate (Cindye DAG-472) is added. At 205F. (96C.), the kier is closed off from the expansion tank to develop pressure. The dyeing is conducted under pressure for two hrs. at 240F. (116C). Bath temperature is then lowered to F. (88C.) and the bath discarded. The dyed yarn then is scoured with 54.5 g. each of Merpol I-lCS and tetrasodium pyrophosphate for 20 min. at 140F. (60C.) to remove surface dye. The dyed yarns finally are removed from the kier and dried with hot compressed air.

The formulation described above provides an attractive, bright fluorescent pink shade on the yarn. Dye wash fastness tests were run on the yarn samples according to the method described in the AATCC Technical Manual, 1968, pages B95 and 96, Test No. 61-1968, Table 1, Method 11A, Evaluation Method 8.1. A rating of 4-5 was obtained indicating little or no color change.

EXAMPLE vu EFFECT OF VARIOUS METAL SALTSON COLOR VALUE K/S The superiority of zinc thiocyanate as complexing agent over the other metal salts and thiocyanates is illustrated by laboratory piece dyeings using a Vista-matic dyeing apparatus. A Dyeings are conducted at bathzfiber ratio of about 60:1 using a jig scoured fabric of plain weave construction containing-120 ends/in. in the warp, and 70 picks/in. in the filling. The yarn in warp and filling is a mixed filament yarn of 60 denier and of the same composition as in Example Vl.

Eight 120 m1. baths are prepared at room temperature, each containing 0.02 g. "MerpoP HCS, 2.4 g. citric acid, 0.03 g. dye with formula, as shown below,

OCH;

and 0.2 g. butyl benaoate '(Cindye" Disc-472 A fabric swatch (2 g.) is introduced into each bath. The effect of various thiocyanates and other salts on dyeability is then determined by adding 0.8 g. of one of the salts shown in Table VI to each dye bath. After 10 minutes, the bath temperature is raised to 212F. (100C) at a rate of 2'F./min. (l.1C./min.). The dyeing is continued for 2 hours at the boil. The dyed swatches then are scoured in a fresh bath containing 0.02 g. e ach of MerpoP' BCS and tetrasodium pyrophosphate for 30 min. at 140F. (60C.) to remove surface dye. Swatches finally are treated for 2 min. at 325F. 163C.) in an oven to remove residual butyl benzoate carrier.

Color value is then determined on each fabric sample and the values shown in Table 6 are obtained. Zinc thiocyanate is shown to be far superior to the other salts, including other thiocyanates, in promoting dyeability of the polyarnide fabric with a cationic dye.

DYEING WITH VARIOUS CATIONIC DYES Thirty-nine separate samples of fabric made from the mixed filament yarn described in Example VI are introduced into 39 separate dye baths, each of which contains 2 percent, based on the weight of fibers, of one of the cationic dyes listed below, and zinc thiocyanate in the amount of 40 percent based on the weight of fibers and 0.1 percent based on the weight of water in the bath. The following standard commercially available cationic dyes were individually used in these baths:

-Basacry Yellow 5 RL Basacry1" Yellow 5 GL Basacryl Yellow 7 GL Maxilon" Yellow 2 RL "Maxilon Br. Flavine l0 GFF Astrazon" Yellow 7 GLL Maxilon" Br. Yellow 7 GLA Macilon" Br. Yellow 5 GL Sevron" Yellow R Astrazon" Yellow 8 GL "Astrazon Yellow GRL Astrazon Golden Yellow GLD Astrazon" Orange L Sevron" Orange G "Maxilon" Br. Orange RA Astrazon Orange 3 RL "Astrazon Pink BL Astrazon" Pink FBB D/L Maxilon" Red BL Sevron Br. Red 4 G Sevron" Br. Red D Astrazon" Pink FG Sevron" Br. Red B "Sevron. Br. Red BN Sevron" Br. Red 2 B Sevron" Br. Red 3 B "Astrazon"Red 6 B "BasacryP Violet RL A Maxilon Br. Green 3 G "Sandocry1 Green BG Du Pont Br. Green Crystals "S evron" Blue 2 G "Maxilon Blue 5 RL Sevron" Blue 5 G "Sandocryl" Blue 2 BGLE Maxilon" Blue 5 G SandocryP' Blue 836 "Sevron Blue EG Sevron Blue ER Each bath is maintained at 90C. The resulting dyed fabric samples are subjected to wash fastness tests using the AATCC-Wash Fastness Test used in Example VI. None of the 39 dyed fabric samples changed in shade and all had a color value rating of 5.

What is claimed is:

l. The process for dyeing polyamide fibers comprising contacting said fibers with an aqueous bath containing a cationic dye and zinc thiocyanate at a temperature of at least 90 C.,

V the amount of zinc thiocyanate in the bath being from 1 to percent based on the weight of said fibers and less than 1.5 percent based on the weight of water in the bath.

2. The process of claim 1 wherein said polyamide is poly(meta-phenylene isophthalamide).

3. The process of claim 2 wherein said bath contains a dye carrier and the temperature of said bath is from 90 to 132 C.

4. The process of claim 1 wherein said polyamide is poly(methylene-di-l ,4cyclohexylene dodecane diamide).

5. The process of claim 4 .wherein said bath contains a dye carrier and the temperature of said bath is from 90 to 132 C. 

2. The process of claim 1 wherein said polyamide is poly(meta-phenylene isophthalamide).
 3. The process of claim 2 wherein said bath contains a dye carrier and the temperature of said bath is from 90* to 132*C.
 4. The process of claim 1 wherein said polyamide is poly(methylene-di-1,4-cyclohexylene dodecane diamide).
 5. The process of claim 4 wherein said bath contains a dye carrier and the temperature of said bath is from 90* to 132*C. 